Rapid advances in technology in several areas have converged to enable small, portable memory cards with vast capacities. Flash memory technologies such as those using electrically-erasable programmable read-only memory (EEPROM) have produced chips storing 128 M-Bytes or more. Small flash-memory cards have been designed that have a connector that can plug into a specialized reader, such as for compact-flash, Secure Digital, Multi-Media Card (MMC) memory stick, or other standardized formats. Both MMC and SD cards have a form factor that is approximately 24 mm wide, 32 mm long, and 1.4 mm or 1.5 mm thick, and are substantially rectangular except for a chamfer formed in one corner, which defines the front end of the card that is inserted into a card-hosting device. Both the MMC and SD card's contact pads are exposed on its lower surface of each card near the front end. Due to the similarities between the MMC and SD form factors and construction, MMC and SD cards are collectively referred to herein as “MMC/SD” cards unless separately specified.
Present MMC/SD memory card manufacturing mainly uses standard surface-mount-technology (SMT) or chip-on-board (COB). Using SMT method to mount electronic components on printed-circuit-board (PCB) has the disadvantage of thickness limitation because the flash memory and controller chips have thickness that is limited by the chip packaging dimension's physical limitation. Also, it would be too costly to stack “packaged” IC chips and it would not be practical at present as both MMC and SD have its own shape, form, standard XY dimensions and thickness. Combining COB assembly methods and plastic molding methods has the disadvantage of plastic flash spilling over the connector pins, which causes poor electrical contact. Also, it is hard to mold multiple PCBA simultaneously per single shot molding.
What is needed is an efficient method for producing MMC/SD devices that avoids the problems associated with conventional methods.